If your children are thirsty, encourage them to drink water- that would be the clear health message from research into taste preferences at Bangor University.

The new research has shown for the first time that overweight and obese people have a dulled sensitivity to soft drinks but enhanced subconscious liking of sweet as a taste. What’s more, the evidence is that even if you are not overweight, drinking two sugary drinks a day for just four weeks is sufficient to dull your sensitivity to the taste sensation and reduce your enjoyment of that, but increase preference for it.

While this news is depressing to those who have a sweet tooth, there are also far more worrying and serious health implications from these findings.

As the sweet ‘treat’ becomes less rewarding, so we tend to look for more sweet food or drink and a vicious circle of eating sweet and calorie laden food is established.

The worrying information when discussing soft drinks, is that we’re not considering the worst examples of sugar-laden carbonated drinks, but levels of sugar found in fruit cordial or ‘squash’ and natural fruit juice as well as carbonated drinks- there are no ‘bad guys’ it seems- they’re all too high in sugar and too sweet.

“This has serious implications for public health. This research shows how little sweet food stuffs are required to actually change your taste perceptions and how powerful sweet tasting products are,” explains Dr Hans-Peter Kubis of the University’s School of Sport, Health & Exercise Sciences.

“We are headed for a multi-level health disaster with rising obesity levels and the increasing incidence of type 2 diabetes. From our research it’s clear to see how this situation may have created a cycle of sweet food and drink consumption. As taste satisfaction levels drop; the more sweet foods are consumed, contributing to these problems.

“Sugar is far more freely available today than was in our diets previously.”

Kubis’ opinion is that this problem needs addressing at a national level:

“My reaction would be to encourage the government to consider taxing sugar that is added to foodstuffs- and have that tax ring fenced for the health budget. I’d also question the wisdom of including fruit juice in the 5 a day message. Fruit juice is higher in sugars than people realise. For example, if you removed the sharp citrus taste from of orange juice you wouldn’t like drinking it as it would be too sweet- in the same way as you wouldn’t consider eating all the oranges that make up a bottle of juice,” he says.

The results were based on experiments carried out at the University’s School of Sport, Health and Exercise Science in collaboration with Bristol University.

In the trial, lean and obese people were asked to rate their perception of and enjoyment of sweet and salty tastes. The initial trial showed that overweight and obese participants actually rated identical drinks as being less sweet in their perception, than that of the lean participants. In further experiments they tested the subconscious preference for sweet food with a computer based test finding that overweight and obese participants had a stronger preference for sweet than lean. The conclusion was that overweight and obese participants had a reduced sensitivity to sweetness but an enhanced subconscious preference for sweet food.

“Our subconscious drive plays a huge role in what food choices we make, and as overweight people feel hungrier they are more affected by their subconscious drive for sweet high calorie foods,” explains Hans-Peter Kubis.

To test whether sweet food consumption may be responsible for these finding and to see if it was possible to recreate the taste perception of obese people in normal weight people,people who don’t usually consume sugary drinks were recruited for a second experiment. They found that in as little as four weeks it was possible to replicate the dulling of the ‘sweetness’ of sugary drinks and lessen the enjoyment just by repeated consumption.

Dr Lucy Donaldson at the University of Bristol School of Physiology and Pharmacology, said: “We have known for some time that the way that we perceive different tastes can change under different circumstances. This finding, that a couple of sweet drinks a day over a short time can dramatically change taste, was a real surprise.”

The research is published in Appetite (2011), doi:10.1016/j.appet.2011.05.107 : Taste perception and implicit attitude toward sweet related to body mass index and soft drink supplementation Dr Kubis explains his work in this video clip.